Urinary incontinence is an involuntary discharge of urine from the bladder. Incontinence can be caused by a variety of factors including pregnancy, estrogen deficiency, general weakening of the spectral pelvic floor muscles, surgery along the urinary tract, infection, and other maladies localized in the urinary tract. In addition to incontinence, women can experience chronic pain and infections along the urinary tract. These conditions are widespread and affect millions of people.
There are several types of incontinence, including stress incontinence, urge incontinence, and total incontinence. Stress incontinence occurs when a person's body is under physical stress. People suffering from this type of incontinence might experience urine discharge during physically stressful events. Examples of stressful events include coughing, laughing, and rigorous exercise.
Urge incontinence is characterized as an urgent desire to urinate and results in total discharge of the bladder. During urge incontinence, the detrusor muscle contracts or spasms inappropriately as the bladder fills. Such a contraction can occur suddenly, without warning, and is frequently accompanied by a strong desire to void the bladder. Unstable bladder activity caused by urge incontinence is a common type of incontinence in females. This type of incontinence can occur at any time, but frequently occurs when a person has a sudden change in their physical position. Total incontinence is characterized by a total lack of control over urine discharge and is frequently caused by complete failure of the sphincter muscles.
For practical purposes, treatments for an unstable bladder are divided into simple and complex therapy. Simply therapy includes behavioral modification and drug therapy, while complex therapy encompasses electrical stimulation and radical surgery, which is performed either to denervate the bladder or to augment its capacity.
When treating detrusor instability, the use of therapeutic agents such as drugs represents a pharmacologic attempt to interfere with bladder smooth muscle contraction. Various agents may work at several different points in the physiologic pathway leading to detrusor contraction. Possible sites of action include modulating control mechanisms in the central nervous system, blocking the activity of acetylcholine (which is the major neurotransmitter in the bladder), directly relaxing bladder smooth muscle, or regulating other substances believed to have a modulating effect on bladder contractile function. Agents that are useful in treating detrusor instability may be broken down into at least six categories: anticholinergic drugs, antispasmodic or spasmolytic drugs, tricyclic antidepressants, calcium channel blockers, prostaglandin synthetase inhibitors, and estrogens.
Because the main neuroreceptor involved in bladder contraction is acetylcholine, most agents used in treating detrusor instability/hyperreflexia are drugs having significant anticholinergic properties, even if these properties are not the main mechanism of action when the drugs are categorized pharmacologically. The prototypical anticholinergic drug is atropine, a powerful belladonna alkaloid that exerts its effects through competitive antimuscarinic activity at parasympathetic neuroreceptor junctions. These effects are felt in many organ systems, including the bladder.
Because these receptors are found in many parts of the body, the use of any anticholinergic drug will produce effects on many physiologic parameters, not just those related to bladder function. Atropine is far more potent than any of the drugs used in the treatment of detrusor over activity. However, there has been little progress in developing anticholinergic drugs that act specifically on the bladder. As a result, the side effect patterns of these other drugs will follow roughly the same dose-response pattern as atropine.
The most common side effects that may be experienced include a dry mouth due to suppression of salivary and oropharyngeal secretions, occasional drowsiness, constipation due to decreased gastrointestinal motility, increased heart rate due to vagal blockade, and transient blurring of vision due to blockade of the sphincter of the iris and the ciliary muscle of the lens of the eye. Delivering agents to treat disorders other than detrusor instability can also cause serious side effects or harm to the patient.
Therefore, there is a need in the art for methods and apparatuses for treating various maladies that effect the urinary tract. There is also a need for methods and apparatuses for delivering an agent to tissue proximal to the urinary tract while minimizing exposure of the agent to other tissue.